New Breakthrough Test Predicts Heart Risk

A promising new test could lower the incidence of coronary artery disease (CAD) by revealing those at risk years in advance and treating them. According to a study published in the Journal of the American College of Cardiology, persons with higher than normal levels of an enzyme called myeloperoxidase (MPO) are at much higher risk of developing CAD.

The case-control study conducted by Dr. Matthijs Boekholdt and his team followed 3,375 apparently healthy volunteers over an eight-year period. The subjects were all from Norfolk, England, and were part of another clinical study called the EPIC (European Prospective Investigation into Cancer and Nutrition) study. A blood test established an initial MPO level for each subject. The results showed that the test subjects who had high levels of MPO initially were at almost 1 1/2 times higher risk of developing CAD than those who had low levels of MPO.

CAD is a condition that occurs when the oxygen-rich blood flow to the heart is partially or completely blocked. When a part of the heart can not get enough oxygen-rich blood, angina, or chest pain, develops. When the blood flow to a part of the heart is completely blocked a heart attack occurs. According to the U.S. Department of Health and Human Services National Institutes of Health, CAD is the most common type of heart disease and is the leading killer of both men and women in the U.S.

MPO is an enzyme that is normally contained in certain types of white blood cells called neutrophils. Neutrophils fight infection and are present during inflammation. When an infective agent is detected by the immune system, neutrophils are dispatched to the location and attack the invader using MPO and other enzymes to destroy it. However, MPO also forms free radicals and promotes oxidative damage of tissues and contributes to the formation of plaques in the blood vessels.

An earlier study published in the November 2001 issue of the Journal of the American Medical Association also supports the hypothesis that elevated levels of MPO indicate CAD. This study followed a much smaller population of subjects for a much shorter period of time, but was still able to reach the conclusion that elevated levels of MPO are an important indicator of CAD.

Currently, the test for MPO is not approved by the FDA for clinical use. It will have to be approved before it can be put into wide-spread use. More research is needed to determine whether MPO levels are a better predictor of CAD than other currently used predictors.

The conclusions of both studies were that elevated levels of MPO predict a future risk of CAD in apparently healthy individuals.

Sources:

National Institutes of Health What is Coronary Artery Disease?

Renliang Zhang, MD,PhD; Marie-Luise Brennan, PhD; Xiaoming Fu, MS; Ronnier J. Aviles, MD; Gregory L. Pearce, MS; Marc S. Penn, MD,PhD; Eric J. Topol, MD; Dennis L. Sprecher, MD; Stanley L. Hazen, MD,PhD, Association Between Myeloperoxidase Levels and Risk of Coronary Artery Disease, The Journal of the American Medical Association

Marijn C. Meuwese, MD, Erik S.G. Stroes, MD, PhD, Stanley L. Hazen, MD, PhD, Joram N. van Miert, BSc, Jan Albert Kuivenhoven, PhD, Robert G. Schaub, PhD, Nicholas J. Wareham, MB, PhD, Robert Luben, BSc, John J.P. Kastelein, MD, PhD, Kay-Tee Khaw, and S. Matthijs Boekholdt, MD, PhD,
"Serum Myeloperoxidase Levels Are Associated With the Future Risk of Coronary Artery Disease in Apparently Healthy Individuals: The EPIC-Norfolk Prospective Population Study," Journal of the American College of Cardiology